UV printing method and system based on real-time self-adaptive compensation and UV printing equipment

Abstract

The invention is suitable for the technical field of printing, and provides a UV printing method and system based on real-time self-adaptive compensation and UV printing device.The method comprises the steps that printing data are received and analyzed, and a reference ink jet instruction of each printing point on a preset printing path is determined according to the printing data; the printing head assembly is driven to move above the printing base material along a preset printing path; in the moving process of the printing head assembly, a composite sensor is used for detecting a to-be-printed micro-area on a preset printing path, and a sensing data stream is obtained; the obtained sensing data flow is analyzed, and a parameter set used for representing the physical characteristics of the to-be-printed micro-region is extracted; calculating and generating a group of compensation parameters in real time based on the extracted parameter set; and synchronously executing real-time compensated printing and curing operations in combination with the compensation parameters and the corresponding reference ink-jet instructions when moving to the accurate position of the to-be-printed micro-area. The problem that an existing printing pattern is not matched with the physical property of the surface of a printing base material is solved.

Description

Technical Field

[0001] The present invention relates to the field of printing technology, and in particular to a UV printing method, system and UV printing equipment based on real-time adaptive compensation. Background Art

[0002] UV printing technology is an advanced digital printing technology that uses an inkjet method to spray UV-curable ink onto the surface of a substrate. Then, through ultraviolet light of a specific wavelength, the liquid ink undergoes a photochemical reaction in an extremely short time, achieving rapid curing and imaging. With its wide range of applicability (printable on virtually all materials, including plastic, glass, metal, wood, and leather), fast curing speed, no need for platemaking, strong image adhesion, wear resistance, and a relatively environmentally friendly process, UV printing technology has been widely used in numerous industries, including advertising signs, decorative building materials, electronic product casings, handicrafts, packaging, and personal protective equipment, becoming a key means of achieving personalized customization and industrialized production.

[0003] However, the high-quality imaging effects of existing UV printing technology rely heavily on a demanding prerequisite: a precise and constant distance (commonly referred to as print height or Z-axis height) must be maintained between the print head nozzle and the surface of the printed substrate. This condition can be easily met when the printed object is an ideal plane. However, in actual applications, more and more printing needs are for non-planar objects, such as curved mobile phone cases and helmet shells, uneven embossed plates, irregularly shaped pebbles or industrial parts, and materials with natural textures (such as wood grain and stone grain).

[0004] When working with these non-flat substrates, the Z-axis distance between the printhead and the underlying, undulating substrate constantly changes as the printhead moves along the XY plane. If the distance is too far, the ejected ink droplets will disperse due to air turbulence during flight, causing the final imaged ink dots to become larger and shifted, blurring the pattern and creating jagged edges, severely reducing print accuracy and clarity. If the distance is too close, there's a risk of the printhead scraping the substrate surface, not only degrading the printed pattern but also potentially causing permanent physical damage to the expensive printhead. This can severely degrade print quality, exposing significant limitations to existing technologies.

[0005] To address the above issues, some solutions have been proposed in this field. One simple approach is to use a print head with a larger depth of field, but this usually comes at the expense of maximum printing accuracy, has a limited scope of application, and cannot handle surfaces with large undulations. Another more mainstream solution is to adopt an offline mode of "scan first, then print." This method uses an independent 3D scanning device (such as a laser scanner) to perform a complete three-dimensional model of the object before printing, and then uses complex software algorithms to plan a printing path for the print head that matches the surface contour of the object and changes in real time on the Z axis. However, this solution has many drawbacks:

[0006] 1. The process is cumbersome and inefficient: Scanning and printing are two separate steps, usually requiring different equipment and software. The entire process is time-consuming and cannot meet the needs of efficient production.

[0007] 2. The system is complex and costly: Additional 3D scanning equipment and professional path planning software are required, which increases the complexity and overall cost of the system.

[0008] 3. Limited accuracy and error accumulation: The final compensation accuracy is limited by the scanning accuracy, model processing accuracy, and the alignment accuracy between the scanning coordinate system and the printing coordinate system. The error accumulation problem is difficult to avoid.

[0009] 4. Lack of dynamic adaptability: This is an open-loop control system. Once the scan is completed, the printing path is fixed. The system cannot dynamically adjust to minor deformations of the material during the printing process (such as thermal expansion and contraction) or slight displacement during initial placement.

[0010] More importantly, even the most advanced offline scanning solutions mentioned above only focus on "single-dimensional geometric compensation," compensating only for Z-axis height. They completely ignore deeper print quality issues caused by variations in surface physical properties:

[0011] Distortion of ink droplet spread: When ink droplets are sprayed onto an inclined surface, gravity and surface tension cause them to stretch or deform, rather than remaining perfectly circular. Existing technologies are unable to compensate for this, leading to inconsistent dot shapes in high-precision microtexture printing, which can severely impact image quality and detail.

[0012] Inconsistent curing energy: UV curing effectiveness is closely related to the energy density of the UV light. Energy density is affected not only by distance (the farther away, the lower the energy), but also by the surface angle (inclined surfaces receive less effective energy) and the optical properties of the material itself (dark or rough surfaces absorb more light). Existing technologies typically use a constant UV lamp power, which inevitably leads to under-curing (sticky ink) or over-curing (brittle ink layer, cracking) at different locations on the substrate.

[0013] Poor integration of printed patterns with native textures: Existing printing technologies essentially perform "overprinting" on the substrate surface. When printing on wood or stone slabs with exquisite natural textures, UV printing equipment is unable to intelligently recognize and utilize these textures. For example, it cannot automatically adjust the print color depth based on the depth of the wood grain. As a result, the printed pattern appears to float on the surface like a sticker, lacking the high-quality, embedded feeling and artistic beauty that blends seamlessly with the substrate.

[0014] In summary, when dealing with the needs of UV printing on non-flat and textured surfaces, the existing technology in this field not only has bottlenecks in operational efficiency and compensation accuracy, but also has serious deficiencies in the dimension and intelligence of compensation. It is unable to solve a series of deep-seated problems such as ink droplet morphology, curing quality and artistic integration caused by the comprehensive changes in surface geometry and physical properties. Summary of the Invention

[0015] Based on this, the purpose of the present invention is to provide a UV printing method, system and UV printing equipment based on real-time adaptive compensation, so as to fundamentally solve the problem of mismatch between existing printed patterns and the physical properties of the printed substrate surface.

[0016] A UV printing method based on real-time adaptive compensation according to an embodiment of the present invention is applied to a UV printing device, and the method includes:

[0017] Receive and analyze print data containing image information, and determine a preset print path and a reference inkjet instruction for each print point along the preset print path based on the print data, wherein the reference inkjet instruction defines the ink color and reference ink volume to be ejected;

[0018] Driving a print head assembly including a UV inkjet nozzle, a UV curing lamp, and a drive mechanism for adjusting the Z-axis height to move above the printing substrate along the preset printing path;

[0019] During the movement of the print head assembly, a composite sensor integrated in the print head assembly and spatially ahead of the UV inkjet nozzle is used to perform real-time and continuous advance detection of a micro-area to be printed on the preset printing path, thereby obtaining a sensor data stream containing three-dimensional topographic data and material optical property data of the micro-area to be printed;

[0020] Parsing the acquired sensor data stream to extract a parameter set for characterizing the physical properties of the micro-region to be printed, the parameter set including a surface normal vector, a precise distance from the UV inkjet nozzle to the surface, and a surface material reflectivity;

[0021] Based on the extracted parameter set, a set of compensation parameters for adaptively adjusting printing behavior is calculated and generated in real time, the compensation parameters including a height adjustment value, a jetting correction value, and a curing energy adjustment value, wherein the jetting correction value is used to define an adjustment to an ink droplet ejection volume or an ejection timing;

[0022] When the UV inkjet nozzle moves to the precise position of the micro-area to be printed, the compensation parameter and the corresponding reference inkjet instruction are combined to synchronously drive the driving mechanism to adjust the height of the print head assembly according to the height adjustment value, control the UV inkjet nozzle to perform inkjet according to the final ejection parameter based on the reference ink volume and the ejection correction value, and adjust the UV curing lamp to output energy according to the curing energy adjustment value, so as to perform real-time compensated printing and curing operations.

[0023] In addition, the UV printing method based on real-time adaptive compensation according to the above embodiment of the present invention may also have the following additional technical features:

[0024] Furthermore, the step of calculating and generating a set of compensation parameters for adaptively adjusting the printing behavior in real time based on the extracted parameter set includes:

[0025] Calculating the height adjustment value based on the precise distance from the UV inkjet nozzle to the surface and the surface normal vector to maintain a predetermined target printing height between the print head assembly and the micro-area to be printed;

[0026] Calculating the ejection correction value based on the surface normal vector to offset the spreading deformation of the ink droplet on the inclined surface represented by the surface normal vector;

[0027] The curing energy adjustment value is comprehensively calculated based on the precise distance from the UV inkjet nozzle to the surface, the surface normal vector, and the reflectivity of the surface material to ensure the consistency of ink layer curing.

[0028] Furthermore, the step of calculating the injection correction value based on the surface normal vector includes:

[0029] determining the surface inclination of the micro-area to be printed according to the surface normal vector;

[0030] Calling a preset fluid dynamics model or an empirical lookup table to predict, based on the surface inclination, the amount of geometric deformation generated by an ink droplet of standard volume spreading on the inclined surface;

[0031] Based on the predicted geometric deformation, a set of adjustment values for adjusting the ink droplet ejection volume or ejection timing that can compensate for the geometric deformation is reversely calculated, and the adjustment values are used as the ejection correction values.

[0032] Furthermore, based on the precise distance from the UV inkjet nozzle to the surface, the surface normal vector, and the reflectivity of the surface material, the step of comprehensively calculating the curing energy adjustment value includes:

[0033] Calculating the energy density attenuation factor of the UV light reaching the printing substrate surface based on the precise distance from the UV inkjet nozzle to the surface and the surface normal vector;

[0034] Determining the UV light absorption efficiency of the printing substrate surface of the micro-region to be printed based on the reflectivity of the surface material;

[0035] The target UV radiation total energy value required to achieve the target curing degree of the ink layer is calculated by combining the energy density attenuation factor and the absorption efficiency, and the curing energy adjustment value is determined based on the relationship between the target UV radiation total energy value and the reference curing energy.

[0036] Furthermore, the step of controlling the UV inkjet nozzle to perform inkjet according to the final ejection parameter based on the reference ink volume and the ejection correction value further includes:

[0037] Normalizing the extracted material optical property data into texture feature values that characterize the depth or characteristics of the texture to reflect the native texture of the printing substrate;

[0038] In a preset color mapping relationship library, searching or interpolating and calculating a corresponding color adjustment vector according to the texture feature value;

[0039] The color adjustment vector is applied to the ink color value of the reference inkjet instruction to form a color output in the final jetting parameters that blends with the native texture of the printing substrate.

[0040] Furthermore, the step of receiving and parsing print data containing image information, and determining a preset print path and a reference inkjet instruction for each print point along the preset print path according to the print data includes:

[0041] Rasterizing the image information in the print data into a pixel matrix consisting of a plurality of pixels and having a predetermined resolution, wherein each pixel has a color value in a source color space;

[0042] A preset printing path is defined as a scanning trajectory covering the printing area corresponding to the pixel matrix, wherein the scanning trajectory is composed of a series of parallel main scanning paths and step displacements perpendicular to the main scanning paths;

[0043] For each pixel in the pixel matrix, a preset configuration file is called through a color management system to convert the color value in the source color space into target color data consisting of multi-channel ink volume values corresponding to the ink channel of the UV printing device;

[0044] Performing halftoning on each channel ink volume value in the target color data to generate a multi-channel ink dot matrix, wherein the value at each position of the ink dot matrix defines a physical state of an ink droplet required to be ejected at the corresponding ink channel at that position, wherein the physical state of the ink droplet is selected from not ejecting or ejecting ink droplets of at least one preset size;

[0045] The position points in the ink dot matrix are spatially mapped to the printing points on the preset printing path, and a reference inkjet instruction is generated for each printing point on the preset printing path based on the spatial mapping relationship. The reference inkjet instruction defines the specific ink color and corresponding reference ink volume required to be sprayed for each printing point.

[0046] Furthermore, the step of obtaining the sensor data stream containing the three-dimensional topography data and material optical property data of the micro-area to be printed includes:

[0047] Using the line laser emitter in the composite sensor, a laser line is projected across the moving direction of the print head assembly onto the surface of the printing substrate in the forward direction of the print head assembly to cover the width of the micro-area to be printed;

[0048] Utilizing the area array image sensor in the composite sensor, which is arranged at a preset angle to the line laser emitter, to continuously capture the laser line image modulated by the surface of the micro-area to be printed in real time;

[0049] Based on the imaging position of the laser line on the area array image sensor and according to the principle of triangulation, the three-dimensional coordinates of each point on the laser line relative to the print head assembly are calculated to generate the three-dimensional topography data;

[0050] At the same time, the multi-spectral point light source or wide-spectrum light source in the composite sensor is used to project detection light to the micro-area to be printed, and a spectral detector is used to receive the light signal reflected back from the surface of the printing substrate, and the optical characteristic data of the material is obtained by analyzing the reflected spectrum.

[0051] Furthermore, the step of parsing the acquired sensor data stream to extract a parameter set for characterizing the physical properties of the micro-region to be printed includes:

[0052] Preprocessing the three-dimensional topography data in the sensor data stream to generate a local surface point cloud, and selecting a plurality of point cloud data in a neighborhood centered around a printing point corresponding to a micro-region to be printed in the local surface point cloud;

[0053] Performing plane fitting or surface fitting on a plurality of point cloud data within the neighborhood to calculate a tangent plane or tangent surface of the printing point position;

[0054] Based on the fitted tangent plane or tangent curved surface, calculating its normal vector at the printing point, and using the normal vector as the surface normal vector;

[0055] Calculating the Z-axis coordinate value of the printed point in the point cloud and, in combination with the current Z-axis coordinate value of the print head assembly, determining the precise distance from the UV inkjet nozzle to the surface;

[0056] Signal processing is performed on the material optical characteristic data in the sensing data stream, and an average reflectivity within a preset wavelength range is extracted from the acquired reflection spectrum, and the average reflectivity is used as the surface material reflectivity.

[0057] Another embodiment of the present invention is to provide a UV printing system based on real-time adaptive compensation, which is applied to a UV printing device. The system includes:

[0058] a data processing module configured to receive and analyze print data containing image information, and determine a preset print path and a reference inkjet instruction for each print point along the preset print path based on the print data, wherein the reference inkjet instruction defines a required ink color and a reference ink volume;

[0059] a drive module for driving a print head assembly comprising a UV inkjet nozzle, a UV curing lamp, and a drive mechanism for adjusting the Z-axis height to move above the printing substrate along the preset printing path;

[0060] a data acquisition module configured to, during movement of the print head assembly, utilize a composite sensor integrated into the print head assembly and spatially ahead of the UV inkjet nozzle to perform real-time, continuous advance detection of a micro-area to be printed on the preset printing path, thereby acquiring a sensor data stream containing three-dimensional topographic data and material optical property data of the micro-area to be printed;

[0061] a sensor analysis module for analyzing the acquired sensor data stream to extract a parameter set for characterizing the physical properties of the micro-region to be printed, the parameter set including the surface normal vector, the precise distance from the UV inkjet nozzle to the surface, and the reflectivity of the surface material;

[0062] a compensation calculation module, configured to calculate and generate a set of compensation parameters for adaptively adjusting printing behavior in real time based on the extracted parameter set, wherein the compensation parameters include a height adjustment value, an ejection correction value, and a curing energy adjustment value, wherein the ejection correction value is used to define an adjustment to an ink droplet ejection volume or an ejection timing;

[0063] The control module is configured to, when the UV inkjet nozzle moves to the precise position of the micro-area to be printed, synchronously drive the drive mechanism to adjust the height of the print head assembly by the height adjustment value, control the UV inkjet nozzle to eject ink using a final ejection parameter based on the reference ink volume and the ejection correction value, and adjust the UV curing lamp to output energy using the curing energy adjustment value, so as to perform real-time compensated printing and curing operations, in combination with the compensation parameter and the corresponding reference inkjet instruction.

[0064] Another embodiment of the present invention is to provide a UV printing device, comprising:

[0065] A print head assembly, which integrates a UV inkjet nozzle, a UV curing lamp, and a drive mechanism for adjusting its Z-axis height;

[0066] A composite sensor, which is mechanically fixed to the print head assembly and arranged at the front end of the printing path of the UV inkjet nozzle in the forward direction;

[0067] a motion assembly for driving the print head assembly to move over a printing substrate; and

[0068] a central controller electrically connected to the print head assembly, the composite sensor, and the motion assembly;

[0069] The central controller is configured to execute the UV printing method based on real-time adaptive compensation as described above.

[0070] The UV printing method based on real-time adaptive compensation provided by the embodiment of the present invention realizes the prediction and prejudgment of the printing path by introducing a composite sensor that is ahead of the nozzle in space. By acquiring the three-dimensional morphology and material characteristics of the micro-area to be printed in real time and performing dynamic compensation, the UV printing device can perform high-quality printing on various irregular, non-planar, textured, curved and even oddly shaped object surfaces; by adjusting the Z-axis height in real time, it is ensured that the UV inkjet nozzle and the printing substrate surface always maintain the optimal printing distance, effectively avoiding ink droplet atomization, focus blur and landing point deviation caused by distance changes, and ensuring the sharpness of the image edge and the clarity of details; by predicting and compensating for the spreading deformation of ink droplets on inclined surfaces, it is ensured that even on steep slopes, each ink dot can maintain its preset ideal geometric shape, thereby perfectly restoring the microscopic texture of the image, which is crucial for printing fine lines, text and geometric patterns, and fundamentally prevents the stretching or Compression distortion; by comprehensively considering the effects of printing distance, surface inclination and material reflectivity on UV energy absorption, the energy output of the UV curing lamp is precisely controlled to ensure that the ink layer can achieve the best curing effect on surfaces of different heights, angles and light absorption characteristics, avoiding the problems of insufficient curing (resulting in poor adhesion and stickiness) or over-curing (resulting in brittleness and cracking of the ink layer) common in traditional technologies, significantly improving the durability, wear resistance and overall physical properties of the printed products; at the same time, through in-depth analysis of the optical properties of the printing substrate material, it can identify the original texture of the printing substrate itself (such as the depth of wood grain, spots of stone, etc.), and intelligently fine-tune the printing color according to preset rules, so that the printed pattern is no longer rigidly attached to the material surface, but can coexist harmoniously with the natural texture of the printing substrate, creating high-value-added products with deeper, more natural and more artistic sense, and solving the problem of mismatch between the existing printed pattern and the physical properties of the printing substrate surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 Schematic diagram of the process of the UV printing method based on real-time adaptive compensation in the first embodiment of the present invention;

[0072] Figure 2 for Figure 1 Specific flow diagram of step S50;

[0073] Figure 3 Schematic diagram of the structure of a UV printing system based on real-time adaptive compensation in a second embodiment of the present invention;

[0074] Figure 4 Schematic diagram of the structure of a UV printing device in a third embodiment of the present invention;

[0075] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0076] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0077] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0078] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0079] Example 1

[0080] See also Figure 1 , which shows a UV printing method based on real-time adaptive compensation in a first embodiment of the present invention. For ease of description, only the parts related to the embodiment of the present invention are shown. The UV printing method based on real-time adaptive compensation provided by the embodiment of the present invention includes:

[0081] Step S10, receiving and parsing print data containing image information, and determining a preset print path and a reference inkjet instruction for each print point along the preset print path based on the print data, wherein the reference inkjet instruction defines the ink color and reference ink volume to be ejected;

[0082] In one embodiment of the present invention, the user sends the image file to be printed (such as a TIF, PDF, JPG, etc. format file) to the UV printing device via a network or USB interface. The UV printing device receives a print task (which usually includes an image information) from a host computer and performs preliminary analysis. The analysis process includes rasterizing the image into a high-resolution pixel matrix and planning the scanning path of the print head assembly, i.e., the preset printing path, based on the device characteristics (such as print head width, resolution) and printing strategy (such as unidirectional / bidirectional printing). At the same time, through the color management system, the color information of each pixel of the image (such as RGB) is converted into the ink volume value corresponding to the UV printing device ink system (such as CMYK, white, varnish, etc.), forming the benchmark inkjet instruction for each printing point.

[0083] Specifically, the steps of receiving and parsing print data containing image information, and determining a preset print path and reference inkjet instructions for each print point along the preset print path according to the print data include:

[0084] Rasterizing the image information in the print data into a pixel matrix consisting of a plurality of pixels with a predetermined resolution, wherein each pixel has a color value in a source color space;

[0085] The preset printing path is defined as a scanning trajectory covering the printing area corresponding to the pixel matrix, wherein the scanning trajectory is composed of a series of parallel main scanning paths and step displacements perpendicular to the main scanning paths;

[0086] For each pixel in the pixel matrix, a preset configuration file is called through a color management system to convert the color value in the source color space into target color data consisting of multi-channel ink volume values corresponding to the ink channel of the UV printing device;

[0087] Performing halftoning on each channel ink volume value in the target color data to generate a multi-channel ink dot matrix, wherein the value at each position of the ink dot matrix defines a physical state of an ink droplet required to be ejected at that position of the corresponding ink channel, wherein the physical state of the ink droplet is selected from not ejecting or ejecting ink droplets of at least one preset size;

[0088] The position points in the ink dot matrix are spatially mapped to the printing points on the preset printing path, and based on the spatial mapping relationship, a baseline inkjet instruction is generated for each printing point on the preset printing path. The baseline inkjet instruction defines the specific ink color and corresponding baseline ink volume required for each printing point.

[0089] Specifically, the image file is first converted into a pixel matrix according to the preset printing resolution (such as 720x1440 DPI). Then, based on the image size and the format of the UV printing device, a raster scanning trajectory covering the entire image area is generated. This trajectory consists of a series of parallel X-axis reciprocating motions (main scanning path) and small steps on the Y axis (step displacement), which serves as the preset printing path. Then, the built-in color management system (CMS) and the ICC profile for the current ink and substrate are called to accurately convert the RGB or Lab color value of each pixel in the pixel matrix into the ink volume value corresponding to the ink channel of the UV printing device (such as CMYK+W (cyan, magenta, yellow, black, white)). Furthermore, the continuous ink volume values are halftoned (for example, using error diffusion or frequency modulation dithering algorithm) to generate a multi-channel ink dot matrix. The value of each dot in the ink dot matrix defines the physical state of the ink droplet that the nozzle of the corresponding color channel needs to spray at that physical position (for example, 0 represents no spraying, 1 represents a small ink droplet (for example, 7pl), 2 represents a medium ink droplet (for example, 14pl), etc.), so that the continuous ink volume value is converted into a discrete ink dot matrix of the presence or size of the ink dot. Finally, the logical ink dot matrix is spatially mapped to the physical printing path, and finally a reference inkjet instruction is generated for each printing point on the path. The reference inkjet instruction is a printing scheme under an "ideal flat surface", which defines the ink color (such as a certain combination of CMYK) and the corresponding reference ink volume (for example, the C channel sprays a 7pl ink droplet, and the Y channel sprays a 14pl ink droplet). Therefore, this step ensures that the printing task has been converted into high-fidelity, device-independent digital instructions before compensation through a professional image processing process, providing a high-quality blueprint for subsequent precise compensation.

[0090] Furthermore, halftone processing can specifically adopt an error diffusion algorithm, which specifically includes: processing the ink volume value of a certain channel in the target color data point by point, starting from a predetermined starting point of the pixel matrix; for the currently processed pixel point, accumulating its ink volume value with the quantization error transmitted from the surrounding processed pixel points to obtain a corrected ink volume value; comparing the corrected ink volume value with a set of preset thresholds corresponding to ink droplets of different sizes to determine the physical state of the ink droplet to be ejected at the current printing point, and generating a corresponding quantized output; calculating the difference between the quantized output and the corrected ink volume value to obtain a new quantization error; distributing and transmitting the new quantization error to its surrounding adjacent pixels that have not yet been processed according to a preset diffusion coefficient.

[0091] Step S20, driving a print head assembly including a UV inkjet nozzle, a UV curing lamp, and a drive mechanism for adjusting the Z-axis height to move above the printing substrate along a preset printing path;

[0092] In one embodiment of the present invention, a UV printing device controls a printhead assembly to move along a predetermined printing path over a printing substrate. The printhead assembly is a highly integrated unit that includes not only UV inkjet nozzles and UV curing lamps, but also a key drive mechanism (such as a precision ball screw or linear motor) for rapidly adjusting the Z-axis height of the printhead assembly.

[0093] Step S30: During the movement of the print head assembly, a composite sensor integrated into the print head assembly and spatially ahead of the UV inkjet nozzles is used to perform real-time, continuous advance detection of the micro-area to be printed on the predetermined printing path, thereby acquiring a sensor data stream containing three-dimensional topographic data and material optical property data of the micro-area to be printed;

[0094] In one embodiment of the present invention, a composite sensor is integrated into the printhead assembly. This composite sensor is specifically mounted in front of the UV inkjet nozzle (along the printing path). For example, during positive X-axis movement, the composite sensor is located in the positive X-axis direction of the UV inkjet nozzle. This allows the composite sensor to proactively detect the tiny area about to be printed (the micro-area to be printed) as the printhead moves, providing real-time, continuous advance detection, generating a sensor data stream containing both 3D topographic data and material optical property data.

[0095] The step of obtaining the sensor data stream containing the three-dimensional topographic data and material optical property data of the micro-area to be printed includes:

[0096] Using the line laser emitter in the composite sensor, a laser line is projected across the moving direction of the print head assembly onto the surface of the printing substrate in the forward direction of the print head assembly to cover the width of the micro-area to be printed;

[0097] The area array image sensor in the composite sensor is arranged at a preset angle to the line laser emitter to continuously capture the laser line image modulated by the surface of the micro-area to be printed in real time;

[0098] Based on the imaging position of the laser line on the area array image sensor and the principle of triangulation, the three-dimensional coordinates of each point on the laser line relative to the print head assembly are calculated to generate three-dimensional topography data;

[0099] At the same time, the multi-spectral point light source or wide-spectrum light source in the composite sensor is used to project detection light to the micro-area to be printed, and a spectral detector is used to receive the light signal reflected back from the surface of the printed substrate, and the optical characteristic data of the material is obtained by analyzing the reflected spectrum.

[0100] Specifically, as the printhead assembly moves along the X-axis, the UV printing device sends a synchronized trigger signal to the composite sensor at a preset frequency (e.g., 100 microseconds). Upon receiving each trigger signal, the line laser emitter in the composite sensor emits a laser pulse with an extremely short duration (e.g., 100 microseconds), forming a transient laser line on the surface of the printing substrate. Almost simultaneously, the global shutter of the area array image sensor, located at a predetermined angle, opens. With an equally short exposure time (e.g., 100 microseconds), it continuously captures, in real time, the image of the laser line, modulated (i.e., distorted and deformed) by the unevenness of the printed substrate surface. If the substrate is flat, the captured image is a straight line; if the substrate is uneven, the captured image is a curved line. Each captured grayscale image frame is immediately transmitted to the FPGA processor within the area array image sensor. The FPGA processor processes the image and, using sub-pixel extraction algorithms such as centroid or Gaussian fitting, accurately locates the center position of each column of pixels along the laser line profile. Finally, the FPGA processor uses these imaging position coordinates and a pre-calibrated, factory-calibrated mathematical model based on triangulation principles (which incorporates the precise geometric relationships between the laser, camera, and lens) to calculate the three-dimensional coordinates (X, Y, Z) of each point on the laser line relative to the sensor coordinate system. This series of (X, Y, Z) coordinate points now constitutes a frame of 3D topography data (i.e., a contour point cloud). If the trigger frequency is 2000Hz, the composite sensor can generate 2000 contour point clouds per second, forming a continuous, high-density 3D topography sensing data stream.

[0101] At the same time, during the movement of the print head, the multi-spectral point light source or wide-spectrum light source in the composite sensor continues to work stably. The spectral detector integrates and collects the received reflected light signals at a frequency (2000Hz) synchronized with the three-dimensional measurement. At this time, each acquisition obtains a reflection spectrum curve covering a preset band (for example, 380nm-780nm). The processor in the sensor can obtain rich material optical property data by analyzing this reflection spectrum curve. For example: calculate the average reflection intensity of the entire spectrum to determine the brightness of the material. Extract the precise reflectivity in a specific band (such as the band where UV curing lamps work). Analyze the shape characteristics of the spectrum for more complex material identification (for example, distinguishing between wood and metal). At this time, the reflection spectrum data obtained through continuous collection and analysis constitutes the material optical property sensing data stream.

[0102] Step S40 , parsing the acquired sensor data stream to extract a parameter set for characterizing the physical properties of the micro-region to be printed, the parameter set including the surface normal vector, the precise distance from the UV inkjet nozzle to the surface, and the reflectivity of the surface material;

[0103] In one embodiment of the present invention, the step of parsing the acquired sensor data stream and extracting a parameter set for characterizing the physical properties of the micro-region to be printed includes:

[0104] Preprocessing the three-dimensional topography data in the sensor data stream to generate a local surface point cloud, and selecting multiple point cloud data in a neighborhood centered around a printing point corresponding to the micro-area to be printed in the local surface point cloud;

[0105] Perform plane fitting or surface fitting on multiple point cloud data within the neighborhood to calculate the tangent plane or tangent surface of the printing point position;

[0106] Based on the fitted tangent plane or tangent surface, the normal vector at the printing point is calculated, and the normal vector is used as the surface normal vector;

[0107] Calculate the Z-axis coordinate value of the printed point in the point cloud and combine it with the current Z-axis coordinate value of the print head assembly to determine the exact distance from the UV inkjet nozzle to the surface;

[0108] Signal processing is performed on the material optical characteristic data in the sensor data stream, and the average reflectivity within a preset band range is extracted from the acquired reflection spectrum, and the average reflectivity is used as the surface material reflectivity.

[0109] Specifically, the UV printer first receives frames of contour point cloud data (3D topography data) from a composite sensor. Due to the high-speed X-axis motion of the print head assembly, the UV printer stitches together several consecutive frames of contour point cloud data (for example, 20 frames corresponding to a physical movement of 0.1 mm) based on the real-time encoder position of the print head assembly to form a denser local surface point cloud covering a small area in front of the UV inkjet nozzle. For each point to be printed along the predetermined print path, the UV printer first determines the corresponding position of the point in the local surface point cloud. Then, using the k-nearest neighbor (k-NN) search algorithm, it quickly selects a predetermined number of nearest neighbor point cloud data around the point, forming a neighborhood point cloud for analysis. Selecting a neighborhood rather than a single point for analysis significantly improves computational stability and noise immunity. This neighborhood point cloud, containing the predetermined number of points, is then subjected to RANSAC or least squares fitting for plane / surface fitting. The normal vector of the fitted tangent plane / surface is the surface normal vector for the print point (indicating its orientation and tilt). While performing the plane fitting, the UV printer also calculates the projection point of the print point onto the fitted tangent plane. The Z-axis coordinate of this projection point represents the most reliable surface height of the print point after smoothing and denoising. The UV printer also records the current Z-axis reference coordinate of the print head assembly in real time (for example, provided by an encoder on the Z-axis drive mechanism). The precise distance between the UV inkjet nozzle and the surface can be determined by subtracting the Z-axis coordinate of the projected print point from the Z-axis reference coordinate of the print head assembly. In parallel with 3D data processing, the UV printer also processes the material optical property data stream from the spectral detector. A moving average filter is first applied to each received raw reflectance spectrum curve to smooth out subtle jitter caused by circuit noise or ambient light fluctuations. The UV curing process mainly relies on ultraviolet light energy in a specific wavelength band. Therefore, the UV printing device will set a preset analysis band based on the emission spectrum characteristics of the UV curing lamp currently in use (for example, for the 395nm band sensitive to UV curing, it can be set to 385nm to 405nm). The UV printing device then calculates the integrated light intensity of the reflectance spectrum curve within this preset band and compares it with the integrated light intensity of a calibrated reference white plate to obtain a standardized average reflectance value (a value between 0 and 1). This calculated average reflectance is used as the surface material reflectance of the printed point.

[0110] Step S50: Based on the extracted parameter set, a set of compensation parameters for adaptively adjusting the printing behavior is calculated and generated in real time, the compensation parameters including a height adjustment value, a jetting correction value, and a curing energy adjustment value, wherein the jetting correction value is used to define the adjustment of the ink droplet ejection volume or ejection timing;

[0111] Among them, reference Figure 2 As shown, in one embodiment of the present invention, the steps of calculating and generating a set of compensation parameters for adaptively adjusting printing behavior in real time based on the extracted parameter set include:

[0112] Step S51 , calculating a height adjustment value based on the precise distance from the UV inkjet nozzle to the surface and the surface normal vector, so as to maintain a preset target printing height between the print head assembly and the micro-area to be printed;

[0113] Step S52: calculating an ejection correction value based on the surface normal vector to offset the spreading deformation of the ink droplet on the inclined surface represented by the surface normal vector;

[0114] In step S53 , a curing energy adjustment value is comprehensively calculated based on the precise distance from the UV inkjet nozzle to the surface, the surface normal vector, and the reflectivity of the surface material to ensure the consistency of the ink layer curing.

[0115] Specifically, the UV printer reads the precise distance from the UV inkjet nozzle to the surface from a parameter set. The UV printer also presets an ideal target print height, which is determined based on ink characteristics and printhead performance to achieve optimal droplet flight and placement accuracy. A preliminary height adjustment value is then determined based on the precise distance from the UV inkjet nozzle to the surface and the target print height. Minor geometric corrections caused by the surface normal are also taken into account to ensure the shortest distance perpendicular to the substrate surface, ultimately determining the height adjustment value.

[0116] The step of calculating the injection correction value based on the surface normal vector includes:

[0117] Determining the surface inclination of the micro-area to be printed based on the surface normal vector;

[0118] Calling a preset fluid dynamics model or empirical lookup table to predict the geometric deformation caused by a standard volume ink droplet spreading on the inclined surface based on the surface inclination;

[0119] According to the predicted geometric deformation, a set of adjustment amounts for compensating for the geometric deformation and adjusting the ejection volume or ejection timing of the ink droplets is reversely calculated, and the adjustment amounts are used as ejection correction values.

[0120] Specifically, the UV printing device obtains the surface normal vector from the parameter set, and calculates the angle between the surface normal vector and the Z-axis unit vector perpendicular to the reference plane of the UV printing device. This angle is the surface inclination of the micro-area to be printed. The UV printing device is preloaded with a fluid dynamics model / empirical lookup table established through a large amount of experimental data or CFD (computational fluid dynamics) simulation. This fluid dynamics model / empirical lookup table predicts or describes the ratio of the major axis to the minor axis (i.e., the geometric deformation) of the final shape of ink droplets of different volumes after spreading on surfaces with different inclinations. Therefore, based on the surface inclination, the geometric deformation caused by a standard volume of ink droplets spreading on an inclined surface can be predicted. In order to compensate for the tensile deformation, it is necessary to reversely calculate the injection strategy that can offset this effect. Specifically, it can be achieved by adjusting the droplet volume (for UV inkjet nozzles that support variable droplet technology) and adjusting the jet timing (changing the flight time or landing position of the droplet). The timing adjustment is for high-speed scanning, fine-tuning the trigger time interval and / or position offset landing point of the jet, which can cause the ink droplets to produce tiny horizontal displacements during flight, shaping the merging and spreading process of the ink droplets, thereby achieving fine-tuning of the landing point on the inclined surface and indirectly compensating for the shape. At this time, adjusting the jet timing will generate a set of complex timing and position fine-tuning adjustments. Adjusting the droplet volume will generate a volume adjustment. At this time, the above parameters used to compensate for geometric deformation are uniformly packaged as jet correction values and output as one of the compensation parameters.

[0121] The step of comprehensively calculating the curing energy adjustment value based on the combination of the precise distance from the UV inkjet nozzle to the surface, the surface normal vector, and the reflectivity of the surface material includes:

[0122] The energy density attenuation factor of the UV light reaching the printing substrate surface is calculated based on the precise distance from the UV inkjet nozzle to the surface and the surface normal vector;

[0123] Determine the UV light absorption efficiency of the printing substrate surface in the micro-area to be printed based on the reflectivity of the surface material;

[0124] The target UV radiation total energy value required to achieve the target curing degree of the ink layer is calculated by combining the energy density attenuation factor and the absorption efficiency. The curing energy adjustment value is determined based on the relationship between the target UV radiation total energy value and the benchmark curing energy.

[0125] The effectiveness of curing energy is primarily affected by distance and angle, with the energy density attenuation factor consisting of two components: the distance attenuation factor and the angle attenuation factor. The UV printer first determines the precise distance and surface normal vector. Based on the inverse square law in physics, the UV light energy density is inversely proportional to the square of the distance, allowing the distance attenuation factor to be calculated. Furthermore, according to Lambert's cosine law, when a surface is tilted (determined by the normal vector), the energy received per unit area decreases with the cosine of the tilt angle, allowing the angle attenuation factor to be calculated. The energy density attenuation factor due to geometric factors is then calculated by multiplying the distance attenuation factor and the angle attenuation factor. The surface material reflectivity is also determined. The UV light absorption efficiency of the printed substrate can be approximately calculated as 1 minus the surface material reflectivity. For example, a dark wood grain with a reflectivity of 0.2 has an absorption efficiency of 0.8, while a bright area with a reflectivity of 0.7 has an absorption efficiency of 0.3. The total energy absorbed by the ink layer is proportional to the product of the total UV radiation energy value, the energy density attenuation factor, and the absorption efficiency. In order to keep the total energy absorbed by the ink layer constant, the target UV radiation total energy value is inversely proportional to the product of the energy density attenuation factor and the absorption efficiency. When the target UV radiation total energy value is calculated, the curing energy adjustment value is determined based on the relationship between the target UV radiation total energy value and the benchmark curing energy required for printing on an ideal plane and standard material set in the UV printing equipment.

[0126] Step S60: When the UV inkjet nozzle reaches the precise position of the micro-area to be printed, the compensation parameter and the corresponding reference inkjet instruction are combined to synchronously drive the drive mechanism to adjust the height of the print head assembly by the height adjustment value, control the UV inkjet nozzle to perform inkjet according to the final ejection parameter based on the reference ink volume and the ejection correction value, and adjust the UV curing lamp to output energy according to the curing energy adjustment value, thereby performing real-time compensated printing and curing operations.

[0127] Among them, in one embodiment of the present invention, since the composite sensor is ahead of the UV inkjet nozzle, the UV printing device has enough (although very short, usually in the millisecond level) time to complete detection, analysis and calculation. When the UV inkjet nozzle of the print head assembly is precisely moved above the micro-area to be printed (i.e., the target printing point) that has been previously detected by the composite sensor, the compensation parameters calculated in the previous step are combined in real time with the reference inkjet instruction generated in the above step S10 to perform the final printing and curing operation. Specifically, the height adjustment value is sent to the drive mechanism, which drives the drive mechanism to fine-tune the UV inkjet nozzle so that the distance between it and the target printing point is always equal to the preset optimal printing height; the jet correction value is combined with the reference ink volume to generate the final jet parameter, and the corresponding UV inkjet nozzle is controlled to perform precise inkjet. The curing energy adjustment value is sent to the power controller of the UV curing lamp, so that it instantly adjusts the output power or irradiation time to achieve just the right curing.

[0128] Furthermore, in one embodiment of the present invention, the step of controlling the UV inkjet nozzle to perform inkjet according to the final ejection parameter based on the reference ink volume and the ejection calibration value further includes:

[0129] Normalizing the extracted material optical property data into texture feature values that characterize the depth or characteristics of the texture to reflect the native texture of the printing substrate;

[0130] In a preset color mapping relationship library, a corresponding color adjustment vector is searched or interpolated based on the texture feature value;

[0131] The color adjustment vectors are applied to the ink color values of the baseline inkjet instructions to produce a color output in the final jetting parameters that blends with the native texture of the printed substrate.

[0132] Specifically, at the moment of inkjet printing, the UV printer retrieves the material optical property data for the current print point from a pre-generated parameter set. This material optical property data (such as reflectivity) is used to characterize the native texture of the printed substrate. To facilitate subsequent mapping calculations, the module normalizes the surface material reflectivity, mapping it to a texture feature value between 0 and 1. Furthermore, the UV printer is preloaded with a color mapping library pre-defined by artists or color experts. This library defines the degree of color adjustment corresponding to different texture feature values. This color mapping library can be a simple two-dimensional table, with input being a texture feature value between 0 and 1 and outputting a color adjustment vector. This color adjustment vector can define adjustments to various color dimensions, such as brightness, saturation, and hue. The texture feature value calculated based on the normalization is then searched within the color mapping library. If the texture feature value falls at an index point in the color mapping library, the corresponding color adjustment vector is directly retrieved. If it falls between two index points, the precise color adjustment vector is calculated through linear interpolation. After determining the color adjustment vector for the current printing point, the UV printing device applies it to the ink color value defined by the original benchmark inkjet instruction for that point. In order to make meaningful color adjustments, the UV printing device will first convert the CMYK ink volume value defined in the benchmark instruction through the reverse ICC profile to a device-independent color space that is more in line with human visual perception, such as CIELAB. In this color space, color is represented by three components: L (brightness), a (red and green), and b (yellow and blue). The color adjustment vector calculated in the previous step is then applied to the Lab value of the current point. The adjusted new Lab value is again converted back to the CMYK ink volume value ultimately required by the UV printing device through the forward ICC profile. At this time, the new CMYK ink volume value adjusted by texture fusion will replace the color part of the original reference instruction, and combine with the physical compensation part (such as the jet correction value) to form the final jetting parameters, which are then handed over to the UV inkjet nozzle for execution. This allows the final ejected color to echo the depth changes of the substrate texture, thereby achieving a highly artistic color output with a high degree of fusion between the printed pattern and the native texture of the printed substrate.

[0133] In summary, the UV printing method based on real-time adaptive compensation in the above embodiments of the present invention realizes the prediction and prejudgment of the printing path by introducing a composite sensor that is ahead of the nozzle in space, and obtains the three-dimensional morphology and material properties of the micro-area to be printed in real time and performs dynamic compensation, so that the UV printing device can perform high-quality printing on various irregular, non-planar, textured, curved and even strangely shaped object surfaces; by adjusting the Z-axis height in real time, it ensures that the UV inkjet nozzle and the printing substrate surface always maintain the optimal printing distance, effectively avoiding ink droplet atomization, focus blur and landing point deviation caused by distance changes, and ensuring the sharpness of the image edge and the clarity of details; by predicting and compensating for the spreading deformation of ink droplets on inclined surfaces, it ensures that even on steep slopes, each ink dot can maintain its preset ideal geometric shape, thereby perfectly restoring the microscopic texture of the image, which is crucial for printing fine lines, text and geometric patterns, and fundamentally prevents the image from being stretched. By comprehensively considering the effects of printing distance, surface inclination and material reflectivity on UV energy absorption, the energy output of the UV curing lamp is precisely controlled, ensuring that the ink layer can achieve the best curing effect on surfaces of different heights, angles and light absorption characteristics, avoiding the problems of under-curing (resulting in poor adhesion and stickiness) or over-curing (resulting in brittle ink layer and cracking) commonly seen in traditional technologies, significantly improving the durability, wear resistance and overall physical properties of the printed products; at the same time, through in-depth analysis of the optical properties of the printing substrate material, it can identify the original texture of the printing substrate itself (such as the depth of wood grain, the spots of stone, etc.), and intelligently fine-tune the printed color according to preset rules, so that the printed pattern is no longer rigidly attached to the material surface, but can coexist harmoniously with the natural texture of the printing substrate, creating high-value-added products with deeper, more natural and more artistic sense, and solving the problem of mismatch between the existing printed pattern and the physical properties of the printing substrate surface.

[0134] Example 2

[0135] See also Figure 3 , is a schematic structural diagram of a UV printing system based on real-time adaptive compensation provided by a second embodiment of the present invention. For ease of explanation, only the parts related to the embodiment of the present invention are shown. The UV printing system based on real-time adaptive compensation in the embodiment of the present invention is applied to a UV printing device, and the system includes:

[0136] The data processing module 11 is configured to receive and analyze print data containing image information, and determine a preset print path and a reference inkjet instruction for each print point along the preset print path based on the print data, wherein the reference inkjet instruction defines the ink color and reference ink volume to be ejected.

[0137] a drive module 12 for driving a print head assembly comprising a UV inkjet nozzle, a UV curing lamp, and a drive mechanism for adjusting the Z-axis height to move above the printing substrate along the preset printing path;

[0138] The data acquisition module 13 is configured to utilize a composite sensor integrated with the print head assembly and spatially ahead of the UV inkjet nozzle to perform real-time, continuous advance detection of a micro-area to be printed on the preset printing path during movement of the print head assembly, thereby acquiring a sensor data stream including three-dimensional topographic data and material optical property data of the micro-area to be printed;

[0139] a sensor analysis module 14 for analyzing the acquired sensor data stream to extract a parameter set for characterizing the physical properties of the micro-region to be printed, the parameter set including the surface normal vector, the precise distance from the UV inkjet nozzle to the surface, and the reflectivity of the surface material;

[0140] a compensation calculation module 15 for calculating and generating, in real time, a set of compensation parameters for adaptively adjusting printing behavior based on the extracted parameter set, the compensation parameters including a height adjustment value, an ejection correction value, and a curing energy adjustment value, wherein the ejection correction value is used to define an adjustment to an ink droplet ejection volume or an ejection timing;

[0141] The control module 16 is configured to, when the UV inkjet nozzle moves to the precise position of the micro-area to be printed, synchronously drive the drive mechanism to adjust the height of the print head assembly by the height adjustment value, control the UV inkjet nozzle to eject ink using a final ejection parameter based on the reference ink volume and the ejection correction value, and adjust the UV curing lamp to output energy using the curing energy adjustment value, so as to perform real-time compensated printing and curing operations, based on the compensation parameter and the corresponding reference inkjet instruction.

[0142] Furthermore, in one embodiment of the present invention, the compensation calculation module 15 includes:

[0143] a height adjustment value calculation unit, configured to calculate the height adjustment value based on the precise distance from the UV inkjet nozzle to the surface and the surface normal vector, so as to maintain a preset target printing height between the print head assembly and the micro-area to be printed;

[0144] an ejection correction value calculation unit, configured to calculate the ejection correction value based on the surface normal vector, so as to offset spreading deformation of the ink droplet on the inclined surface represented by the surface normal vector;

[0145] The curing energy adjustment value calculation unit is used to comprehensively calculate the curing energy adjustment value based on the precise distance from the UV inkjet nozzle to the surface, the surface normal vector and the reflectivity of the surface material to ensure the consistency of ink layer curing.

[0146] Furthermore, in one embodiment of the present invention, the injection correction value calculation unit includes:

[0147] a surface inclination determination subunit, configured to determine the surface inclination of the micro-region to be printed according to the surface normal vector;

[0148] a geometric deformation determination subunit, configured to call a preset fluid dynamics model or an empirical lookup table to predict, based on the surface inclination, the geometric deformation generated by an ink droplet of standard volume spreading on the inclined surface;

[0149] The ejection correction value determination subunit is used to reversely calculate a set of adjustment values for ink droplet ejection volume or ejection timing based on the predicted geometric deformation, which can compensate for the geometric deformation, and use the adjustment values as the ejection correction values.

[0150] Furthermore, in one embodiment of the present invention, the curing energy adjustment value calculation unit includes:

[0151] an energy density attenuation factor calculation subunit, configured to calculate an energy density attenuation factor of the UV light reaching the surface of the printing substrate based on the precise distance from the UV inkjet nozzle to the surface and the surface normal vector;

[0152] an absorption efficiency calculation subunit, configured to determine the absorption efficiency of the printing substrate surface of the micro-region to be printed to UV light according to the reflectivity of the surface material;

[0153] The curing energy adjustment value calculation subunit is used to comprehensively calculate the energy density attenuation factor and the absorption efficiency to calculate the target UV radiation total energy value required for the ink layer to reach the target curing degree, and determine the curing energy adjustment value based on the relationship between the target UV radiation total energy value and the reference curing energy.

[0154] Furthermore, in one embodiment of the present invention, the control module 16 includes:

[0155] A texture feature value acquisition unit is used to normalize the extracted material optical characteristic data into a texture feature value representing the depth or characteristics of the texture, so as to reflect the original texture of the printing substrate;

[0156] A color adjustment vector calculation unit is used to search or interpolate and calculate a corresponding color adjustment vector in a preset color mapping relationship library according to the texture feature value;

[0157] The color adjustment vector application unit is configured to apply the color adjustment vector to the ink color value of the reference inkjet instruction, so as to form a color output that blends with the native texture of the printing substrate in the final jetting parameters.

[0158] Furthermore, in one embodiment of the present invention, the data processing module 11 includes:

[0159] An information rasterization unit, configured to rasterize the image information in the print data into a pixel matrix consisting of a plurality of pixels with a predetermined resolution, wherein each pixel has a color value in a source color space;

[0160] a preset printing path definition unit, configured to define the preset printing path as a scanning trajectory covering the printing area corresponding to the pixel matrix, wherein the scanning trajectory is composed of a series of parallel main scanning paths and step displacements perpendicular to the main scanning paths;

[0161] a color value conversion unit, configured to convert, for each pixel in the pixel matrix, a color value in a source color space of the pixel into target color data consisting of multi-channel ink volume values corresponding to an ink channel of the UV printing device, by calling a preset configuration file through a color management system;

[0162] a halftone processing unit configured to perform halftone processing on the ink volume value of each channel in the target color data to generate a multi-channel ink dot matrix, wherein the value at each position of the ink dot matrix defines a physical state of an ink droplet required to be ejected at the corresponding ink channel at that position, wherein the physical state of the ink droplet is selected from not ejecting or ejecting ink droplets of at least one preset size;

[0163] A reference inkjet instruction generation unit is used to spatially map the position points in the ink dot matrix with the printing points on the preset printing path, and generate a reference inkjet instruction for each printing point on the preset printing path based on the spatial mapping relationship. The reference inkjet instruction defines the specific ink color and corresponding reference ink volume required to be sprayed for each printing point.

[0164] Furthermore, in one embodiment of the present invention, the data acquisition module 13 includes:

[0165] a laser line projection unit, configured to project a laser line across the moving direction of the print head assembly onto the surface of the printing substrate in the forward direction of the print head assembly using the line laser emitter in the composite sensor, so as to cover the width of the micro-area to be printed;

[0166] a laser line image capturing unit, configured to capture in real time and continuously the laser line image modulated by the surface of the micro-area to be printed, using the area array image sensor in the composite sensor, which is arranged at a preset angle to the line laser emitter;

[0167] a three-dimensional shape data generating unit for calculating the three-dimensional coordinates of each point on the laser line relative to the print head assembly based on the imaging position of the laser line on the area array image sensor and the principle of triangulation, thereby generating the three-dimensional shape data;

[0168] The material optical characteristic data acquisition unit is used to simultaneously use the multi-spectral point light source or wide-spectrum light source in the composite sensor to project detection light to the micro-area to be printed, and use a spectral detector to receive the light signal reflected from the surface of the printing substrate, and obtain the material optical characteristic data by analyzing the reflected spectrum.

[0169] Furthermore, in one embodiment of the present invention, the sensor analysis module 14 includes:

[0170] a data preprocessing unit configured to preprocess the three-dimensional topography data in the sensor data stream to generate a local surface point cloud, and select, from the local surface point cloud, a plurality of point cloud data in a neighborhood centered around a printing point corresponding to a micro-region to be printed;

[0171] a point cloud data fitting unit, configured to perform plane fitting or surface fitting on a plurality of point cloud data within the neighborhood, and calculate a tangent plane or a tangent surface of the printing point position;

[0172] a normal vector calculation unit, configured to calculate a normal vector of the fitted tangent plane or tangent curved surface at the printing point, and use the normal vector as a surface normal vector;

[0173] a precise distance calculation unit, configured to calculate the Z-axis coordinate value of the printing point in the point cloud and, in combination with the current Z-axis coordinate value of the print head assembly, determine the precise distance from the UV inkjet nozzle to the surface;

[0174] The surface material reflectivity extraction unit is used to perform signal processing on the material optical characteristic data in the sensing data stream, extract the average reflectivity within a preset band from the acquired reflection spectrum, and use the average reflectivity as the surface material reflectivity.

[0175] The UV printing system based on real-time adaptive compensation provided in the embodiment of the present invention has the same implementation principle and technical effects as those in the aforementioned method embodiment. For the sake of brief description, for matters not mentioned in the device embodiment, reference can be made to the corresponding content in the aforementioned method embodiment.

[0176] Example 3

[0177] Another aspect of the present invention also provides a UV printing device, see Figure 4 , which is shown as a UV printing device in a third embodiment of the present invention, includes:

[0178] The print head assembly 10 is integrated with a UV inkjet nozzle, a UV curing lamp, and a drive mechanism for adjusting its Z-axis height;

[0179] A composite sensor 20, which is mechanically fixed to the print head assembly and arranged at the front end of the printing path of the UV inkjet nozzle in the forward direction;

[0180] A motion assembly 30 for driving the print head assembly to move above the printing substrate; and

[0181] a central controller 40 electrically connected to the print head assembly, the composite sensor, and the motion assembly;

[0182] The central controller 40 is configured to execute the UV printing method based on real-time adaptive compensation as described in the above embodiment.

[0183] The printhead assembly 10 is the core of the printing process, integrating multiple UV inkjet nozzles (typically a multi-channel array of nozzles including CMYK, white, and varnish), a UV curing lamp (preferably an LED UV lamp with rapidly adjustable power), and a drive mechanism for precise Z-axis height adjustment (e.g., a ball screw mechanism driven by a stepper motor or servo motor). The composite sensor 20 is compactly mounted at the front end of the printhead assembly 10, with its detection center spatially ahead of the UV inkjet nozzle's ejection position to achieve "preemptive detection." The composite sensor 20 integrates a line laser emitter and an area array image sensor for 3D topography measurement, as well as a spectral detector for measuring material optical properties. The motion assembly 30, typically a gantry or lead screw system driven by X- and Y-axis servo motors, drives the printhead assembly along the X-axis (main scanning direction) and Y-axis (stepping direction) above the printing substrate to complete the predetermined printing path. The central controller 40 is typically an embedded system based on a high-performance processor (such as an FPGA, DSP, or multi-core CPU). It is electrically connected to the print head assembly 10 , the composite sensor 20 and the motion assembly 30 via a high-speed bus, and is used to execute the method described in the above embodiment.

[0184] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0185] The above-described embodiments merely illustrate several embodiments of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A UV printing method based on real-time adaptive compensation, characterized in that: Applied to UV printing equipment, the method includes: Receive and analyze print data containing image information, and determine a preset print path and a reference inkjet instruction for each print point along the preset print path based on the print data, wherein the reference inkjet instruction defines the ink color and reference ink volume to be ejected; Driving a print head assembly including a UV inkjet nozzle, a UV curing lamp, and a drive mechanism for adjusting the Z-axis height to move above the printing substrate along the preset printing path; During the movement of the print head assembly, a composite sensor integrated in the print head assembly and spatially ahead of the UV inkjet nozzle is used to perform real-time and continuous advance detection of a micro-area to be printed on the preset printing path, thereby obtaining a sensor data stream containing three-dimensional topographic data and material optical property data of the micro-area to be printed; Parsing the acquired sensor data stream to extract a parameter set for characterizing the physical properties of the micro-region to be printed, the parameter set including a surface normal vector, a precise distance from the UV inkjet nozzle to the surface, and a surface material reflectivity; Based on the extracted parameter set, a set of compensation parameters for adaptively adjusting printing behavior is calculated and generated in real time, the compensation parameters including a height adjustment value, a jetting correction value, and a curing energy adjustment value, wherein the jetting correction value is used to define an adjustment to an ink droplet ejection volume or an ejection timing; When the UV inkjet nozzle moves to the precise position of the micro-area to be printed, the compensation parameter and the corresponding reference inkjet instruction are combined to synchronously drive the driving mechanism to adjust the height of the print head assembly according to the height adjustment value, control the UV inkjet nozzle to perform inkjet according to the final ejection parameter based on the reference ink volume and the ejection correction value, and adjust the UV curing lamp to output energy according to the curing energy adjustment value, so as to perform real-time compensated printing and curing operations.

2. The UV printing method based on real-time adaptive compensation according to claim 1, characterized in that: The step of calculating and generating a set of compensation parameters for adaptively adjusting the printing behavior in real time based on the extracted parameter set includes: Calculating the height adjustment value based on the precise distance from the UV inkjet nozzle to the surface and the surface normal vector to maintain a predetermined target printing height between the print head assembly and the micro-area to be printed; Calculating the ejection correction value based on the surface normal vector to offset the spreading deformation of the ink droplet on the inclined surface represented by the surface normal vector; The curing energy adjustment value is comprehensively calculated based on the precise distance from the UV inkjet nozzle to the surface, the surface normal vector, and the reflectivity of the surface material to ensure the consistency of ink layer curing.

3. The UV printing method based on real-time adaptive compensation according to claim 2, characterized in that: The step of calculating the injection correction value based on the surface normal vector includes: determining the surface inclination of the micro-area to be printed according to the surface normal vector; Calling a preset fluid dynamics model or an empirical lookup table to predict, based on the surface inclination, the amount of geometric deformation generated by an ink droplet of standard volume spreading on the inclined surface; Based on the predicted geometric deformation, a set of adjustment values for adjusting the ink droplet ejection volume or ejection timing that can compensate for the geometric deformation is reversely calculated, and the adjustment values are used as the ejection correction values.

4. The UV printing method based on real-time adaptive compensation according to claim 2, characterized in that: The step of comprehensively calculating the curing energy adjustment value based on the precise distance from the UV inkjet nozzle to the surface, the surface normal vector, and the reflectivity of the surface material includes: Calculating the energy density attenuation factor of the UV light reaching the printing substrate surface based on the precise distance from the UV inkjet nozzle to the surface and the surface normal vector; Determining the UV light absorption efficiency of the printing substrate surface of the micro-region to be printed based on the reflectivity of the surface material; The target UV radiation total energy value required to achieve the target curing degree of the ink layer is calculated by combining the energy density attenuation factor and the absorption efficiency, and the curing energy adjustment value is determined based on the relationship between the target UV radiation total energy value and the reference curing energy.

5. The UV printing method based on real-time adaptive compensation according to claim 1, characterized in that: The step of controlling the UV inkjet nozzle to jet ink based on the final jetting parameter of the reference ink amount and the jetting correction value further includes: Normalizing the extracted material optical property data into texture feature values that characterize the depth or characteristics of the texture to reflect the native texture of the printing substrate; In a preset color mapping relationship library, searching or interpolating and calculating a corresponding color adjustment vector according to the texture feature value; The color adjustment vector is applied to the ink color value of the reference inkjet instruction to form a color output in the final jetting parameters that blends with the native texture of the printing substrate.

6. The UV printing method based on real-time adaptive compensation according to claim 1, characterized in that: The steps of receiving and parsing print data containing image information, and determining a preset print path and reference inkjet instructions for each print point along the preset print path according to the print data include: Rasterizing the image information in the print data into a pixel matrix consisting of a plurality of pixels and having a predetermined resolution, wherein each pixel has a color value in a source color space; A preset printing path is defined as a scanning trajectory covering the printing area corresponding to the pixel matrix, wherein the scanning trajectory is composed of a series of parallel main scanning paths and step displacements perpendicular to the main scanning paths; For each pixel in the pixel matrix, a preset configuration file is called through a color management system to convert the color value in the source color space into target color data consisting of multi-channel ink volume values corresponding to the ink channel of the UV printing device; Performing halftoning on each channel ink volume value in the target color data to generate a multi-channel ink dot matrix, wherein the value at each position of the ink dot matrix defines a physical state of an ink droplet required to be ejected at the corresponding ink channel at that position, wherein the physical state of the ink droplet is selected from not ejecting or ejecting ink droplets of at least one preset size; The position points in the ink dot matrix are spatially mapped to the printing points on the preset printing path, and a reference inkjet instruction is generated for each printing point on the preset printing path based on the spatial mapping relationship. The reference inkjet instruction defines the specific ink color and corresponding reference ink volume required to be sprayed for each printing point.

7. The UV printing method based on real-time adaptive compensation according to claim 1, characterized in that: The step of obtaining a sensor data stream containing the three-dimensional topography data and material optical property data of the micro-area to be printed comprises: Using the line laser emitter in the composite sensor, a laser line is projected across the moving direction of the print head assembly onto the surface of the printing substrate in the forward direction of the print head assembly to cover the width of the micro-area to be printed; Utilizing the area array image sensor in the composite sensor, which is arranged at a preset angle to the line laser emitter, to continuously capture the laser line image modulated by the surface of the micro-area to be printed in real time; Based on the imaging position of the laser line on the area array image sensor and according to the principle of triangulation, the three-dimensional coordinates of each point on the laser line relative to the print head assembly are calculated to generate the three-dimensional topography data; At the same time, the multi-spectral point light source or wide-spectrum light source in the composite sensor is used to project detection light to the micro-area to be printed, and a spectral detector is used to receive the light signal reflected back from the surface of the printing substrate, and the optical characteristic data of the material is obtained by analyzing the reflected spectrum.

8. The UV printing method based on real-time adaptive compensation according to claim 1, characterized in that: The step of parsing the acquired sensor data stream to extract a parameter set for characterizing the physical properties of the micro-region to be printed includes: Preprocessing the three-dimensional topography data in the sensor data stream to generate a local surface point cloud, and selecting a plurality of point cloud data in a neighborhood centered around a printing point corresponding to a micro-region to be printed in the local surface point cloud; Performing plane fitting or surface fitting on a plurality of point cloud data within the neighborhood to calculate a tangent plane or tangent surface of the printing point position; Calculating a normal vector of the fitted tangent plane or tangent curved surface at the printing point, and using the normal vector as a surface normal vector; Calculating the Z-axis coordinate value of the printed point in the point cloud and, in combination with the current Z-axis coordinate value of the print head assembly, determining the precise distance from the UV inkjet nozzle to the surface; Signal processing is performed on the material optical characteristic data in the sensing data stream, and an average reflectivity within a preset wavelength range is extracted from the acquired reflection spectrum, and the average reflectivity is used as the surface material reflectivity.

9. A UV printing system based on real-time adaptive compensation, characterized in that: Applied to UV printing equipment, the system includes: a data processing module configured to receive and analyze print data containing image information, and determine a preset print path and a reference inkjet instruction for each print point along the preset print path based on the print data, wherein the reference inkjet instruction defines a required ink color and a reference ink volume; a drive module for driving a print head assembly comprising a UV inkjet nozzle, a UV curing lamp, and a drive mechanism for adjusting the Z-axis height to move above the printing substrate along the preset printing path; a data acquisition module configured to, during movement of the print head assembly, utilize a composite sensor integrated into the print head assembly and spatially ahead of the UV inkjet nozzle to perform real-time, continuous advance detection of a micro-area to be printed on the preset printing path, thereby acquiring a sensor data stream containing three-dimensional topographic data and material optical property data of the micro-area to be printed; a sensor analysis module for analyzing the acquired sensor data stream to extract a parameter set for characterizing the physical properties of the micro-region to be printed, the parameter set including the surface normal vector, the precise distance from the UV inkjet nozzle to the surface, and the reflectivity of the surface material; a compensation calculation module, configured to calculate and generate a set of compensation parameters for adaptively adjusting printing behavior in real time based on the extracted parameter set, wherein the compensation parameters include a height adjustment value, an ejection correction value, and a curing energy adjustment value, wherein the ejection correction value is used to define an adjustment to an ink droplet ejection volume or an ejection timing; The control module is configured to, when the UV inkjet nozzle moves to the precise position of the micro-area to be printed, synchronously drive the drive mechanism to adjust the height of the print head assembly by the height adjustment value, control the UV inkjet nozzle to eject ink using a final ejection parameter based on the reference ink volume and the ejection correction value, and adjust the UV curing lamp to output energy using the curing energy adjustment value, so as to perform real-time compensated printing and curing operations, in combination with the compensation parameter and the corresponding reference inkjet instruction.

10. A UV printing device, characterized in that: include: A print head assembly, which integrates a UV inkjet nozzle, a UV curing lamp, and a drive mechanism for adjusting its Z-axis height; A composite sensor, which is mechanically fixed to the print head assembly and arranged at the front end of the printing path of the UV inkjet nozzle in the forward direction; A motion assembly, configured to drive the print head assembly to move above a printing substrate; as well as a central controller electrically connected to the print head assembly, the composite sensor, and the motion assembly; The central controller is configured to execute the UV printing method based on real-time adaptive compensation according to any one of claims 1 to 8.

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